1. Field of the Invention
This invention relates to a duct type air conditioning system (AC system), which is capable of energy efficiently regulating temperature in each room (or zone) independently as well as providing other air conditioning functions such as ventilation, humidifying, cleaning and filtering air in each room independently.
2. Background Information
In most residential houses, one or more central HVACs (heating, ventilation and air-conditioning) are used to send conditioned air to designated rooms. Usually, one thermostat controls the temperature of several rooms or zones. Due to differences in ventilation efficiency and exterior thermal load among different zones, not all zones can achieve the temperature set at the single thermostat control. It is common that rooms on the upper floor have much higher temperature in the summer than rooms in lower floor. In winter, rooms in northwest corner or above the garage of a house usually have lower temperatures than other rooms. With a single thermostat, occupants in different zones cannot select their own comfort level. Moreover, for a zone where the thermostat is not located to reach a certain level, all other zones have to rise or fall at the same time. This is a great waste of energy. Therefore, it is highly desirable that the temperature and possibly other air comfort and quality measures in each zone can be controlled individually.
These solutions, however, are usually complex and expensive and thus hard to justify from cost saving point of view. For example, the solutions by Parker et al. (U.S. Pat. Nos. 4,530,395, 4,646,964, 4,931,948) require dampers fitted inside ducts, thus incurring high installation and maintenance costs. Ho et al. (U.S. Pat. No. 5,833,134) use dampers in registers to control airflows, but the design calls for the register dampers to be manually controlled, thus barring the possibility of automatic zone temperature control. Hampton et al. (U.S. Pat. No. 5,271,558) require turbines be placed in the register and the turbines be connected to power generators. Their invention does not have coordination among zone thermostats either. The current invention presents a simple and inexpensive individual-zone controlled HVAC system.